can, may, shall, will (see usage note at the current entry; see usage note at shall; see synonym study at will)

Usage note

Can1 and may1 are frequently but not always interchangeable in senses indicating possibility: A power failure can (or may) occur at any time. Despite the insistence by some, that can means only “to be able” and may means “to be permitted,” both are regularly used in seeking or granting permission: Can (or May) I borrow your tape recorder? You can (or may) use it tomorrow. Sentences using can occur chiefly in spoken English. May in this sense occurs more frequently in formal contexts: May I address the court, Your Honor? In negative constructions, can't or cannot is more common than may not: You can't have it today. I need it myself. The contraction mayn't is rare. Can but and cannot but are formal and now somewhat old-fashioned expressions suggesting that there is no possible alternative to doing something. Can but is equivalent to can only: We can but do our best.Cannot but is the equivalent of cannot help but: We cannot but protest against these injustices. See also cannot, help.

can2

[kan] /kæn/

noun

1.

a sealed container for food, beverages, etc., as of aluminum, sheet iron coated with tin, or other metal:

Absorbing the third sense of "to know," that of "to know how to do something" (in addition to "to know as a fact" and "to be acquainted with" something or someone). An Old English preterite-present verb, its original past participle, couth, survived only in its negation (see uncouth), but cf. could. The present participle has spun off as cunning.

"to put up in cans," 1860, from can (n.1). Sense of "to fire an employee" is from 1905. Related: Canned; canning.

n.

Old English canne "a cup, container," from Proto-Germanic *kanna (cf. Old Saxon, Old Norse, Swedish kanna, Middle Dutch kanne, Dutch kan, Old High German channa, German Kanne). Probably an early borrowing from Late Latin canna "container, vessel," from Latin canna "reed," also "reed pipe, small boat;" but the sense evolution is difficult.

Modern "air-tight vessel of tinned iron" is from 1867 (can-opener is from 1877). Slang meaning "toilet" is c.1900, said to be a shortening of piss-can. Meaning "buttocks" is from c.1910.